If u r using a servletrunner, then u can call the servlet from the html like this:
If u have a form inside the html, u r form tag will look like this:
<form action="http://localhost:8080/servlet/servletname" method=post>

This will ensure that only post requests can be sent. So u can't reload the serlvet.

One idea is to have the <form>-tag which calls the servlet in a separate "invisible" frame, i.e <frameset cols="100%,*">, and have a JavaScript alter and submit the form when some event is triggered. This way, the shown HTML-page won't be reloaded/refreshed.